Ocet 2010 m.tech. Microelectronics

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OCET 2010Code No.: 210101

Important : Please consult your Admit Card / Roll No. Slip before filling your Roll Number on the TestBooklet and Answer Sheet.

Roll No. In Figures In Words

O.M.R. Answer Sheet Serial No.

Signature of the Candidate :

Subject : M.Tech. (Microelectronics)Time : 90 minutes Number of Questions : 75 Maximum Marks : 75

DO NOT OPEN THE SEAL ON THE BOOKLET UNTIL ASKED TO DO SOINSTRUCTIONS1. Write your Roll No. on the Question Booklet and also on the OMR Answer Sheet in the space provided

and nowhere else.

2. Enter the Subject and Code No. of Question Booklet on the OMR Answer Sheet. Darken thecorresponding bubbles with Black Ball Point / Black Gel pen.

3. Do not make any identification mark on the Answer Sheet or Question Booklet.4. To open the Question Booklet remove the paper seal(s) gently when asked to do so.5. Please check that this Question Booklet contains 75 questions. In case of any discrepancy, inform the

Assistant Superintendent within 10 minutes of the start of test.

6. Each question has four alternative answers (A, B, C, D) of which only one is correct. For each question,

darken only one bubble (A or B or C or D), whichever you think is the correct answer, on the Answer Sheetwith Black Ball Point / Black Gel pen.

7. If you do not want to answer a question, leave all the bubbles corresponding to that question blank in theAnswer Sheet. No marks will be deducted in such cases.

8. Darken the bubbles in the OMR Answer Sheet according to the Serial No. of the questions given in the

Question Booklet.9. Negative marking will be adopted for evaluation i.e., 1/4th of the marks of the question will be deducted

for each wrong answer. A wrong answer means incorrect answer or wrong filling of bubble.

10. For calculations, use of simple log tables is permitted. Borrowing of log tables and any other material is notallowed.

11. For rough work only the sheets marked Rough Work at the end of the Question Booklet be used.

12. The Answer Sheet is designed for computer evaluation. Therefore, if you do not follow the instructions

given on the Answer Sheet, it may make evaluation by the computer difficult. Any resultant loss to thecandidate on the above account, i.e., not following the instructions completely, shall be of the

candidate only.13. After the test, hand over the Question Booklet and the Answer Sheet to the Assistant Superintendent on duty.14. In no case the Answer Sheet, the Question Booklet, or its part or any material copied/noted from this

Booklet is to be taken out of the examination hall. Any candidate found doing so, would be expelled from

the examination.15. A candidate who creates disturbance of any kind or changes his/her seat or is found in possession of any

paper possibly of any assistance or found giving or receiving assistance or found using any other unfairmeans during the examination will be expelled from the examination by the Centre Superintendent/Observer whose decision shall be final.

16. Telecommunication equipment such as pager, cellular phone, wireless, scanner, etc., is notpermitted inside the examination hall. Use of calculators is not allowed.


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1. MOSFET and BJT differ in

(A) Transconductance (B) Packing density

(C) Noise immunity (D) All of the above

2. Transconductance of a MOSFET is

(A) High for low overdrive voltage (B) Lower for low overdrive voltage

(C) Independent of overdrive voltage (D) Varies as cube of overdrive voltage

3. Fermi energy level in tunnel diodes is

(A) Middle of the energy gap

(B) Slightly above the intrinsic Fermi level

(C) Inside the valence and conduction bands

(D) Slightly below the intrinsic Fermi level

4. HBTs are :

(A) Heterojunction Base transistors (B) Heterojunction Bipolar transistors

(C) Hermetic Bipolar transistors (D) A class of MOSFETs

5. The conductivity of same size p-MOSFETs and n-MOSFET is

(A) Same

(B) Conductivity of n-MOSFET is greater than p-MOSFET

(C) Conductivity of p-MOSFET is greater than n-MOSFET

(D) There is no relation between conductivity and type of a MOSFET6. Phase change memories use

(A) Set and Reset operations

(B) Program and Read operations

(C) Crystalline silicon as their base material

(D) Six transistors for their operation

7. A FG device is a

(A) Single gate device

(B) One control gate and one floating gate device(C) Two control gates and one floating gate device

(D) Two control gates, two floating gates and two oxides

8. Which one of the following is not a short channel effect in MOSFETs ?

(A) Drain induced barrier lowering (B) Mobility reduction

(C) Velocity saturation (D) Kirk effect

M.Tech. (Microelectronics)/210101/DNB-11693 1 [Turn over

M.Tech. (Microelectronics)/210101


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9. As per ITRS, which one of the following is not a technology node ?

(A) 130 nm (B) 90 nm

(C) 75 nm (D) 45 nm

10. ITRS stands for

(A) International technology roadmap for semiconductors

(B) International teaching roadmap for semiconductors

(C) Indian technology roadmap for semiconductors

(D) Indian technology roadmap for silicon

11. Intrinsic semiconductors have

(A) Higher conductivity than extrinsic semiconductors

(B) Lower conductivity than extrinsic semiconductors

(C) Same conductivity as compared to extrinsic semiconductors

(D) Fermi level closer to valence band

12. The ratio of electron mobility to diffusion constant has the units of

(A) Temperature (B) No units

(C) (Volt)1 (D) (m)1

13. SEM is used to

(A) Scan surface features (B) Determine crystal structure

(C) Determine heavy metal in solutions (D) None of the above

14. Vander Paw method is used for

(A) Crystal structure of a material

(B) Sheet Resistivity measurement

(C) Inductance and Capacitive measurement

(D) Atomic arrangement determination

15. The energy of the electron beam in SEM is of the order of

(A) 100200 GeV (B) 100200 KeV

(C) 1030 KeV (D) 1030 eV

16. Energy of TEM(A) Is greater than that of SEM (B) Is lesser than that of SEM

(C) Is same as that of SEM (D) None of the above

17. Powder X-ray diffractometry is used to

(A) Determine the crystal structure (B) Determine the surface features

(C) Determine the energy of X-rays (D) None of the above

M.Tech. (Microelectronics)/210101/DNB-11693 2


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18. AFM and STM are used for

(A) Surface atomic layer analysis (B) Determining the energy of electrons

(C) Resistivity measurement (D) Generating diffraction patterns

19. Which of the following is true about LEED ?

(A) It is used for determining X-ray wavelength (B) It is low energy electron diffraction(C) It is high energy electron diffraction (D) It is low energy electron depletion.

20. The difference between AFM and STM is

(A) STM is used for insulating materials and AFM for conductive materials

(B) STM is used for conductive materials and AFM for insulating materials

(C) STM is used for surface details and AFM for Inner details.

(D) STM is based on atomic forces and AFM on quantum tunnelling.

21. MOS inversion layers can be

(A) Weak (B) Moderate

(C) Strong (D) All of the above

22. Four probe method is used for

(A) Bulk resistivity measurements (B) Dielectric constant measurement

(C) Capacitance measurement (D) Inductance measurement

23. Lanthanum oxide is a

(A) Conductor (B) Semiconductor

(C) Dielectric (D) Superconductor

24. TEM gives the information about

(A) Inner crystal defects and structure (B) Surface feature details(C) Atomic wise details (D) Tunnelling currents

25. The following is not an ion based technique

(A) RBS (B) SIMS

(C) SIMOX (D) None of the above

26. Silicon diodes do not emit light because

(A) Their bandgap is direct

(B) Their bandgap is indirect

(C) They are poorly fabricated for light emitting function

(D) None of the above

27. MEMS is

(A) Mechanical and microelectronics technology on a same chip

(B) Some form of a design tool

(C) A MOSFET model

(D) Process of doping



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28. The solar cells are generally made up of

(A) Crystalline materials

(B) Non crystalline materials

(C) Polycrystalline materials

(D) None of the above29. Which of the following statements is true about FRAM memories ?

(A) They are made of very high dielectric constant materials

(B) They are made of very low dielectric constant materials

(C) They are volatile memories

(D) Use amorphous materials for their fabrication

30. Fatigue and imprint terms are associated with which memories ?

(A) 6T-SRAM (B) 1T FRAM

(C) 4T-2R SRAM (D) 1T-DRAM

31. In a MOSFET, the drain to source ON current increases slightly in saturation region

only in the case of

(A) Channel length modulation

(B) Shorting of drain with source

(C) Drain induced barrier lowering

(D) Kirk effect

32. Gain of a MOSFET can be increased by

(A) Decreasing trans-conductance and increasing output resistance

(B) Decreasing trans-conductance and output resistance

(C) Increasing trans-conductance and decreasing output resistance

(D) Increasing trans-conductance and output resistance

33. Which one of the following is a resist material in IC fabrication ?

(A) XPS (B) RBS

(C) SPSS (D) PBS

34. To reduce latch up problem in Integrated Circuits the following technology is useful

(A) Bulk silicon technology (B) SOI technology

(C) SiC technology (D) SiGe technology

35. The silicon crystal method CZ converts

(A) MGS to EGS (B) EGS to MGS

(C) No conversion takes place (D) Amorphous silicon to crystalline silicon

36. Ion implantation in ICs converts silicon substrate from

(A) Polycrystalline to crystalline (B) Amorphous to crystalline

(C) Amorphous to polycrystalline (D) Crystalline to amorphous



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37. X-ray lithography is used for

(A) Transferring of pattern over the resist

(B) Transferring the pattern directly over oxide

(C) Transferring the pattern directly over the silicon

(D) None of the above

38. AAS is used to determine

(A) The mass of the sample

(B) The surface characteristics

(C) The presence of heavy metal in the sample

(D) The charge on the sample

39. Which one of the following is widely used LED material ?

(A) GaAs (B) SiGe

(C) SiC (D) Si

40. Gain of a transistor falls at higher frequencies because

(A) Negative feedback due to parasitic capacitances

(B) Positive feedback due to parasitic capacitances

(C) Early effect

(D) Negative feedback due to emitter resistance

41. The core of an optical fibre is made of(A) Plastic of Glasses (B) Semiconductors

(C) Metals (D) None of the above

42. Mass Spectrometry is an instrument in which

(A) Molecular Mass of the compound is determined

(B) The powdered sample is broken into vapours and then ions for analysis

(C) The ions are separated by the application of magnetic fields

(D) All of the above

43. LN2

is required for

(A) High temperature measurements

(B) Extreme high temperature measurements

(C) Low temperature measurements

(D) Extreme low temperature measurements



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44. A developer solution in IC fabrication is used to

(A) Remove the exposed resist material

(B) Remove the defects in oxides

(C) Remove the surface roughness of the oxide

(D) Remove impurities in the material

45. Contact resistances occur in

(A) AFM measurements (B) SEM measurements

(C) TEM measurements (D) Four probe measurements

46. Bremsstrahlung X-rays are produced by

(A) Discrete energy loss by the electron in the atom

(B) Continuous energy loss by the electron in the atom

(C) Both of the above (D) None of the above

47. In microelectronics terminology, in general,

(A) MNOS and NMOS are the same (B) 1nm = 106 m

(C) Si, Ge, InP and GaAs are dielectrics (D) Al2O

3and SiO

2are dielectrics

48. SONOS is a

(A) Semiconductor nonvolatile memory (B) Digital inverter

(C) Amplifier (D) MOS Transmission gate

49. C4 process is

(A) Testing process

(B) Crystal growth process

(C) Package to die attachment technique

(D) Doping technique

50. Static RAMs store data on the basis of

(A) Change of crystalline state (B) Tunnelling process

(C) Latchup technique (D) Electronic polarization

51. Ferroelectric dynamic memories are based on the principle of

(A) Set-Reset operation

(B) Quantum Mechanical Tunnelling process

(C) Spontaneous polarization

(D) Latching action

52. Level 1, Level 2 and BSIM are

(A) MOSFET models

(B) BJT models

(C) Radhard techniques

(D) Some phenomenon related to energy levels in semiconductors



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53. In a MOSFET, the threshold voltage is a function of

(A) Substrate concentration (B) Oxide thickness

(C) Flatband voltage (D) All of the above

54. Which one of the following is used as a wet etchant in IC fabrication ?

(A) SIMS (B) PMMA

(C) XRD (D) HF

55. Body effect

(A) Raises threshold voltage (B) Reduces threshold voltage

(C) Has no effect on threshold voltage (D) First raises and then reduces

56. Strained silicon technology is used to

(A) Reduce drain to source currents in MOSFETs

(B) Raise drain to source currents in MOSFETs

(C) Has no effect on drain to source currents in MOSFETs

(D) Raises electron effective mass and increases scattering

57. EKV and HiSIM are

(A) An analytical instrument used in surface imaging

(B) MOSFET models

(C) Packaging materials

(D) None

58. The correct order of the electron mobility in the following semiconductors is(A) Strained Si < bulk Si

(B) GaAs < Si

(C) Strained Si > bulk Si

(D) Si > GaAs > Ge

59. The transconductance of a MOSFET in the presence of high energy radiation

(A) Reduces (B) Increases

(C) Remains same (D) First increases and then decreases

60. S-Edit, TSPICE, IC station are the terms associated with

(A) IC fabrication process (B) VLSI design flow

(C) Testing techniques (D) MOSFET modelling techniques

61. Flicker noise in a MOSFET is

(A) High frequency noise (B) Low frequency noise

(C) Both high and low frequency noise (D) None



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62. Which of the following technique in general, is not used for thickness measurement

of a semiconductor sample ?

(A) Absorption technique (B) Ellipsometry technique

(C) Interference technique (D) AES

63. Dynamic power dissipation in a digital circuit can be minimized by(A) Reducing supply voltage (B) Reducing load capacitance

(C) Reducing input clock frequency (D) All of the above

64. Poly-silicon depletion in a MOSFET

(A) Decreases gate capacitance

(B) Increases gate capacitance

(C) Has no effect on gate capacitance

(D) Increases inversion charge density in the substrate

65. Wet oxidation is faster than dry oxidation because

(A) Water diffuses faster than oxygen

(B) Water diffuses slower than oxygen

(C) Same diffusion constant of water and oxygen

(D) None

66. Which of the following about plasma and its applications is false ?

(A) Electrical resistance is infinite (B) It is neutral

(C) It is used in dry etching (D) It is produced from a gas

67. A 6T SRAM Cell consists of

(A) Four pass transistors and two memory cell transistors

(B) Two pass transistors and four memory cell transistors

(C) Three pass transistors and three memory cell transistors

(D) None

68. Electron mobility reduces in short channel MOSFETs because of

(A) Large vertical and lateral electric fields in the substrate

(B) Small electric fields in the channel

(C) Electron tunnelling from source to drain

(D) Electron tunnelling from source to substrate

69. IGBT is a

(A) Transformer (B) MOSFET model

(C) Short channel effect (D) Power electronic device



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70. 1T DRAM has

(A) Write, Read and refresh operations (B) Write and Read operations

(C) Read and refresh operations (D) Write and refresh operations

71. When a reverse bias of 34V is applied to P-N junction silicon diode, the effective

barrier potential is :

(A) 34 V (B) 41 V

(C) 54 V (D) 0 V

72. Which of the following law helps to estimate pins in a VLSI package ?

(A) Ohms law (B) Rents law

(C) Hooks law (D) Ficks law

73. A tunnel diode and a Zener diode operate in one of the following conditions

(A) Forward bias and reverse bias respectively

(B) Reverse bias and forward bias respectively

(C) Both reverse bias

(D) Both forward bias

74. Which of the following is true for the depletion width in a P-N Junction diode ?

(A) It increases with increase in reverse bias

(B) It decreases with increase in reverse bias

(C) Is independent of reverse bias

(D) It increases with increase in doping concentration

75. Which of the following devices is used for microwave frequencies ?

(A) GUNN Diode (B) MESFET

(C) IMPATT (D) All of the above



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M.Tech. (Microelectronics)/210101/DNB-11693 11 130

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Ocet 2010 m.tech. Microelectronics

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